Barca are not officially owing FDJ. The deffered payment wasnt a deffered perse. My guess would be that FDJ in covid times agreed to a paycut with barca offering an incrementally larger wage in year 3 to account for covid. Maybe 100k 200k and 300k after 2nd year onwards.
I also assume there's no legal binding or penalty accrued since it's practically a new contract made before the wages are accrued so it's not officially a debt.
Morally speaking Barcelona are owing FDJ money sure. Perhaps.
FDK would probably lose some potential earning if he moved to United in his 2nd year since the big wages would start to kick in in the 3rd year.
Barcelona do not officially force FDJ out. And up to this point hasnt made a move that can be categorised as forcing a player unethically. Like benching him or sending him to train with kids like we did with BFS. So when it comes to court there's no legal standing in Barcelona trying to force him out. Vague comments made by media arent submittable officially. Barcelona did accept a formidable bid by United, and that's not the same with forcing a player out. At least legally.
FDJ would love his money, rightly so. In no condition of being forced out. Was brought touring, and probably would continue to get game time if he stays.
Barcelona also in no hurry to sell or go bust. They got that covered somehow with their leverage. Stupid moves? Who cares. Laporta is save for a good few years ahead.
Barcelona probably had a decision to just accept the bid. It's a win win. FDJ move they saved money. FDJ stays, no problemo. They might even force United to cover his wages. It's a right logical move since their survival dont hinge on FDJ being sold.